Sinofsky indicated that his new title will be "Executive in Residence" and involve "research, writing, classroom on prod dev, planning, collaboration, and more."

Sinofsky left Microsoft in mid-November after over 20 years with the company, three of them at the helm of the Windows division. Many expected him to eventually succeed Steve Ballmer as Microsoft's CEO. Sinofsky was widely credited for Windows 7's success, particularly after the unpopular Vista. His departure came less than a month after he oversaw the launch of Windows 8, which represented a dramatic overhaul of the Windows operating system and Microsoft's first major push into touch-based computing.

Microsoft gave no official reason for Sinofsky's exit, though many industry watchers speculated that Sinofsky's prickly relationship with top Microsoft executives and controlling management style contributed to him parting ways with the company.

However, Sinofsky said in an internal memo that his exit was a planned decision, not the result of personality clashes.

"Some might notice a bit of chatter speculating about this decision or timing," Sinofsky wrote in the memo. "I can assure you that none could be true as this was a personal and private choice that in no way reflects any speculation or theories one might read -- about me, opportunity, the company or its leadership."